Is there a way that I can check if a data attribute exists?

Is there some way that I can run the following:

var data = $("#dataTable").data('timer');
var diffs = [];

for(var i = 0; i + 1 < data.length; i++) {
    diffs[i] = data[i + 1] - data[i];
}

alert(diffs.join(', '));

Only if there is an attribute called data-timer on the element with an id of #dataTable?

Solution 1:

if ($("#dataTable").data('timer')) {
  ...
}

NOTE this only returns true if the data attribute is not empty string or a "falsey" value e.g. 0 or false.

If you want to check for the existence of the data attribute, even if empty, do this:

if (typeof $("#dataTable").data('timer') !== 'undefined') {
  ...
}

Solution 2:

if (typeof $("#dataTable").data('timer') !== 'undefined')
{
    // your code here
}

Solution 3:

In the interest of providing a different answer from the ones above; you could check it with Object.hasOwnProperty(...) like this:

 if( $("#dataTable").data().hasOwnProperty("timer") ){
     // the data-time property exists, now do you business! .....
 }

alternatively, if you have multiple data elements you want to iterate over you can variablize the .data() object and iterate over it like this:

 var objData = $("#dataTable").data();
 for ( data in objData ){
      if( data == 'timer' ){
            //...do the do
      }
 }

Not saying this solution is better than any of the other ones in here, but at least it's another approach...

Solution 4:

Or combine with some vanilla JS

if ($("#dataTable").get(0).hasAttribute("data-timer")) {
  ...
}